What I kept from this is backtracking, main item and boss for 2d, main room, main item and boss for 3d, also exploration, fighting enemies and play around with the main item.The funniest level design is Twilight Princess, which speaks for itself.

But again, it really depend on how you see and how you'll design a certain dungeon, i mean, in a Link Between worlds, the main item is deleted to focus on exploration, same in Breath of the Wild.

In Breath of the Wild, there is a lot of "Find your path" in the dungeons. There is no main item because you get them all at the start of the game, but there is still a condition to unlock new passages.

Very interesting channel. I watch a lot of video yesterday, not only the Boss Keys one. I love how he draws the graphs in the end, very clear and smooth. I'm wondering what he'd think of the Mystery of Solarus DX (and XD) games clearly, the 6th and 7th dungeons are a lot of find your path, while others are just follow the path. Maybe these games are too close to ALTTP to really break the formula he establised for this one.

I am gonna take notes on these videos. I think information like this would be very useful in the game development section of the book I am working on. Also, I could add more ideas to the brainstorm post.

An interesting remark is that when you have a key and a multiple choice of doors to unlock, the graph may become different depending on that choice (that is not completely the case in key cavern of LA, though). This is easier to see if we allow to have color keys and one color key gives such a choice; with color keys the graph thing could even become much more complex, depending on the choices.

An example to explain what I mentioned would be a dungeon with only 1 red key and only 1 blue key, but several red locks and several blue locks. This is a weird example of dungeon with more locks than keys (completionists may not like the idea of having locks that cannot be opened, though). There would be multiple solutions, which also adds more replayability to the game. Buth this is also a double-edged sword for the devs since they are forced to check that all choices allow to solve the dungeon, without "breaking" the game, heheh.